9. Diatomic and Triatomic Molecules and Sulfur Fluorides

  1. E. C. M. Chen and
  2. E. S. D. Chen

Published Online: 19 APR 2004

DOI: 10.1002/0471659894.ch9

The Electron Capture Detector and the Study of Reactions with Thermal Electrons

The Electron Capture Detector and the Study of Reactions with Thermal Electrons

How to Cite

Chen, E. C. M. and Chen, E. S. D. (2004) Diatomic and Triatomic Molecules and Sulfur Fluorides, in The Electron Capture Detector and the Study of Reactions with Thermal Electrons, John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/0471659894.ch9

Publication History

  1. Published Online: 19 APR 2004
  2. Published Print: 16 APR 2004

ISBN Information

Print ISBN: 9780471326229

Online ISBN: 9780471659891

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Keywords:

  • diatomic anions;
  • triatomic anions;
  • sulfur fluoride anions;
  • anion bond orders;
  • excited anion states;
  • linear anions;
  • bent anions;
  • adiabatic electron affinity;
  • vertical electron affinity

Summary

In Chapter 9, the electron affinities of diatomic and triatomic molecules and SFn(n = 1–6) will be considered. The ECD has been used to study Cl2, Br2, I2, NO, O2, CO2, COS, CS2, N2O, NO2, SO2, SF6. The homonuclear diatomic molecules are the simplest closed set of molecules. Many of the electron affinities of the main group diatomic molecules have been measured by anion photoelectron spectroscopy. These Ea can be examined by their systematic variation in the periodic table. The calculation of Morse potential energy curves for the anions and the comparison with curves for isoelectronic species confirms experimental values. The homonuclear diatomic anions of IA, IB, VI, VII and 3d elements and NO are examined first. Next, electron affinities and Morse potential energy curves for triatomic molecules will be considered. The experimental Ea for CO2, COS, CS2, and N2O are uncertain. These are linear in the neutral form and bent in the anion. The valence state electron affinities are very different ranging from a negative value for CO2 to 0.89(2) eV for CS2. Anions of SFn(n = 1–6) provide a transition to larger molecules. The precise and accurate adiabatic electron affinity of SF6 was measured independently. Values that differ from this value have been assigned to excited anion states. Morse potential energy curves were constructed. The ground state curve of SF6(−) is compared with an ab-initio calculation. By analogy, the Morse curves for other SFn(−) are calculated. These illustrate the use of excited states to explain the different Ea reported for these compounds.